Plugging water sands by a hydratable material



Dec. 29, 1936 A N 2,065,512

PLUGGING WATER SANDS BY A HYDRATABLE MATERIAL Filed Oct. 17, 1954 FlawOur-L er Patented Dec. 29, 1936 UNITED STATES PLUGGING WATER SANDS BY AHYDRATABLE MATERIAL George E. Cannon, Houston, Tex., assignor toStandard Oil Development Company, a corporation of Delaware ApplicationOctober 17, 1934, Serial No. 748,578

5 Claims.

This invention relates to improvements in excluding water from oil andgas wells.

In producing oil or gas from a well, water frequently enters the wellalong with the oil or gas. Production of water in this manner isundesirable and frequently attempts are made to shut off the flow ofwater by cementing the lower portion of the well or by driving lead woolinto the bottom of the well. methods commonly in use, it frequentlyhappens that a portion of the oil-bearing stratum is plugged off alsoand the oil contained in such stratum is lost. In some cases the exactposition of the formation which is producing water is not known or is sosituated that it is impossible to use the cement or lead wool method forplugging the water off.

It is an object of this invention to plug waterbearing sands encounteredin oil wells without affecting the oil-bearing sands.

Other objects would be apparent from the specification and from theaccompanying drawing, in which latter the figure is a diagrammaticrepresentation of a preferred apparatus for carrying out the invention.

Referring particularly to the drawing, reference numeral i designatesthe bore of a well into which extends a string of tubing 2. The portionof the tubing 2 protruding from the surface of the earth is providedwith a T-shaped coupling 5. The T-shaped coupling 5 is provided withpipes 6, l, and 8. The tubing 2 extends substantially throughout thelength of the bore l of the well. The bore of the well pierces stratasuch as l0 and II, which are composed of water-bearing sand which flowsinto the tubing 2 of the well and is delivered with oil and gas from theoil-bearing sand Hi.

The water from the water-bearing sands l0 and II is prevented fromflowing into the bore l of the well by pumping into the well as by thepipe 8 a fluid from a suitable source of supply l5 by means of a pumpIS. The fluid flows downwardly through the casing 2 to the end of thecasing and then it flows upwardly and is delivered through a line ll.The fluid is maintained under sufllcient pressure by the pump IE tocause the fluid to overcome the hydrostatic head of the water in theporous strata "land II and forces its way into the porous sandpermeating the water-bearing strata to the desired extent. The water inthe sands l0 and It contains soluble inorganic salts such as sodiumchloride, calcium chloride, magnesium chloride, and the like. The fluid,on contact with the water in the sand, forms In shutting off water bythe a solid substance within the interstices of the sand at 20, whichplugs the pores of the sand and renders it impervious to water flow.

The fluid used comprises a suspension of a material which swells oncontact with water.- 5 The base of the fluid is a non-aqueous medium,which preferably is miscible with water. The material is inertphysically to oil. The material used may be such hydratable material ashydratable clays, for example bentonite. Gelatin, 10 agar agar, and likematerial which swell on contact with water can also be used. Thehydratable materials can be suspended in anynonaqueous medium such ascrude oil, gas oil or the like, but preferably in a medium such asalcohol, 15 glycerine or the like, which is miscible with water. Theaddition of lime and dispersing agents such as oleic acid may be addedto aid in suspending the hydratable material in the non-aqueous mediumfor convenience in han- 20 dling the suspension. Other members of thefatty acid series, the soaps of fatty acids, soaps of naphthenic acidsand sulfonated naphthenic compounds may be used as dispersing agents forthe suspension, if desired. 25

By way of specific example, the following composition may be cited:

Per cent by volume Isopropyl alcohol 84.5 Bentonite 10.0 30 Lime 5.0Oleic acid 0.5

In this compound the isopropyl alcohol is the non-aqueous suspendingmedium, the bentonlte is the hydratable material which swells on 0011-35 tact with water, the lime and the oleic acid are suspending ordispersing agents which are added to make the suspension more stable andeasier to handle. Either the lime or the oleic acid, or

The composition is pumped from the reservoir I5 into the well undersufllcient pressure to cause 50 the composition to pass into thewater-bearing sands I0 and II, where the colloidal material is wetted bythe water present in the sand, and hydration takes place which increasesthe volume of the solid particles substantially filling the in- Mterstices oi the sand, as designated at 20, resulting in thepermeability of the sand being reduced tosuch an extent that it isimpossible for water to flow from the sand into the well. The portion ofthe hydratable material which is forced into the oil-producing formationII is not hydrated and the particles do not'increase in size. Whenproduction of oil or gas from the well is resumed, the portion oi thesuspensesoid which has entered the oil sand is washed out and thepermeability of this portion of the sand is not appreciably attected.The hydratable material which has entered the water-producing formationsII and ii is trapped due to its having increased in size, re-

sulting in permanentlypiugging the water-bearing sands II and ii.

Various changes may be made within the scope of the appended claims, in.which it is desired to claim all novelty inherent in the invention.

I claim:

1. A process (or plugging oi! water producing sands in a well producingboth oil and water, comprisingintroducing into the well a suspension inoil 0! a solid material inert to oil but which swells on contact withwater and permitting the suspension to flow into both the oil andwaterbearing sands whereby the suspension on contact with the water inthe water-bearing sand swells to plug the pores of only thewater-bearing sand to forms sealagainst the further entrance of waterinto the well. i V a l 2. A process for plugging oil water producingsand in a wellproduclng both oil and water, comprising introducing intothe well a suspension in a non-aqueous medium oi a solid material inertto the medium and to the oil which solid material swells on contact withwater and permitting the suspension to flow into both the oil andwaterbearing sands whereby the material contacts the water in thewater-bearing sand and swells to plug the pores oi only thewater-bearing sand swells to plug the pores oi only the water-bear ingjsand to form a seal against the further entrance 0! water into the wellwhile permitting iree ilow oi oil-from the oil-bearing sand.

4. A process for plugging oil water producing sand in a well producingboth oil and water, comprising introducing into the well a suspension ofa hydratabie clay in a non-aqueous medium to cause the suspension toiiow into both the oil and water-bearing sands whereby the hydratableclay contacts the water in the water-bearing sand and swells taping thepores of only the water-bearing sand to form a seal against theiurtherentrance of water into the well whilepermitting iree flow of oil fromthe oil bearing sand.

5. A process for plugging oil water producing sand in a well producingboth oil and water. comprising introducing into the well a suspension ofgelatine in a non-aqueous medium to cause the gelatine to flow into boththe water and oil-bearing sands whereby the gelatine contacts the waterin the water-bearing sand and swells to plug the pores at only thewater-bearing sand to form a seal against iurther entrance of water intothe well while permitting iree ilow of oil from the oil-bearing sand.

GEORGE E. CANNON.

